A latex prepared from an essentially linear silicone and a silsesquioxane having a grain size of from 1 to 100 nm is described in U.S. Pat. No. 3,355,406 to Cekada, Jr. Stable silicone emulsions comprising .alpha.,.omega.-dihydroxypolydiorganosiloxane, a low-molecular-weight silicone resin, a catalyst and additional substances are described in European Pat. No. EPA 143,877 (published June 2, 1985, W. Grape et al).
The present invention differs from U.S. Pat. No. 3,355,406 in that the silsesquioxane (silicone resin) has a particle size of at least 200 nm, which significantly simplifies the preparation thereof. In contrast to European Pat. No. EP-A 143,877, a high-molecular-weight silicone resin is employed in the present invention, which reduces the amount of emulsifier and thixotropic agent required.
It is, therefore, an object of the present invention to provide novel aqueous silicone dispersions which are stable on storage over a long period of time. Another object of the present invention is to provide aqueous silicone dispersions containing small amounts of emulsifiers and/or thixotropic agents. Still another object of the present invention is to provide aqueous silicone dispersions which may be prepared in a simple and inexpensive manner. A further object of the present invention is to provide aqueous silicone dispersions which vulcanize to form elastomers after evaporation of the water, that adhere to the substrates upon which they are applied prior to vulcanization. A still further object of the present invention is to provide silicone coatings and sealants from aqueous silicone dispersions which vulcanize to form elastomers upon evaporation of the solvent.